Hot plate comprising a coating applied to the lower side thereof

ABSTRACT

A cooktop plate includes a base plate having a lower side. A coating is formed on the lower side of the base plate and includes at least two metal layers and at least two dielectric layers in such a manner that a first color parameter a* or a second color parameter b* of the cooktop plate has a value greater than +10 or smaller than −10.

The invention relates to a cooktop plate, on the lower side of which a coating is configured with metal layers and dielectric layers.

Very differing designs of such embodiments of cooktop plates are known. Such an embodiment is known from U.S. Pat. No. 37,718,929 B2. However there the coating is limited in that the number of layers comprising a protective anti-oxidation layer and a light-screening layer is between 2 and 4. The generation of visual effects relating to the overall visual impression of the cooktop plate is restricted with such embodiments.

The object of the present invention is to create a cooktop plate on the lower side of which a coating is configured with a number of layers, thereby allowing a wider range of possible visual effects in respect of the appearance of the color of the cooktop plate.

Said object is achieved by a cooktop plate having the features claimed in claim 1.

An inventive cooktop plate has a base plate, which has a coating on its lower side. The coating comprises metal layers and dielectric layers. The coating is configured at least with two metal layers and at least two dielectric layers. The coating is additionally configured by means of this number and the specific layers so that a first color parameter a* or a second color parameter b* has a value >+10 or <−10 on the cooktop plate.

The two color parameters a* and b* together with the third color parameter L* form the known standardized CIE system. In this rectangular coordinate system spanned by the three color parameters, the color parameter L* indicates the position on the light/dark axis as a value. The color parameter a* indicates the position on the red/green axis as a value. The further color parameter b* indicates the position on the blue/yellow axis as a value.

Such an embodiment of the coating in respect of the number and type of layers and in respect of the resulting values for two specific color parameters allows much greater possibility of variation with regard to the generation of an overall visual impression of the cooktop plate.

The coating is preferably configured such that a degree of transmission of the cooktop plate in the wavelength range between 380 nm and 780 nm is <12%, in particular between 0.5% and 10%.

The coating is preferably configured such that the third color parameter L* has a value >40, in particular between 40 and 70. This significantly increases the possibility of variation in respect of the widest variety of visual appearances of the cooktop plate. This possibility can therefore be extended still further in conjunction with the larger number of layers in the coating.

Provision is preferably made for the number of metal layers to be 2 or 3.

Provision is made in particular for the number of dielectric layers to be between 2 and 4.

Provision is made for the coating to have a protective layer, in particular a protective anti-oxidation layer, as its lower termination.

The layer sequence is configured in particular, when viewed from the lower side in a downward direction, as starting first with a dielectric layer, followed by a metal layer, then another dielectric layer and then another metal layer. Further dielectric and metal layers can follow. The lower termination of the coating in a downward direction is then formed by the protective layer.

Provision is preferably made for the metal layers and the dielectric layers each to have layer thicknesses of <=100 nm.

Provision is made in particular for at least two metal layers of the coating to have different layer thicknesses and/or at least two dielectric layers of the coating to have different layer thicknesses. This allows an extremely broad palette of different colors to be achieved highly individually and in nuances.

The layers of the coating are preferably configured by sputtering on the lower side, in particular by magnetron sputtering. Provision can preferably be made for the material to comprise a metal layer SSt (stainless steel), Mo, Ni, Cr, Nd, V, Ti, Ta, Si, Al, Cu, W or a combination of at least two of the cited elements.

In respect of the material of a dielectric layer provision is preferably made for this to comprise SnO_(x), ZnO_(x), TiO_(X), AlO_(x), SiO_(x), NbO_(X), TaO_(x), SiN_(x), AlN_(x), TiN_(X), CrN_(x) or a combination of at least two of the cited compounds.

It should be noted that the cooktop plate is configured with a base plate made of glass or glass ceramic, on which the coating is then configured.

In one preferred exemplary embodiment provision is made for the coating to have a first dielectric layer with SnO_(x) with a layer thickness of 76 nm. The coating has a first metal layer with SSt with a layer thickness of 18 nm following this first dielectric layer. Following this first metal layer a second dielectric layer is again configured with SnO_(x) with a layer thickness of 68 nm. Following this a second metal layer is then configured with SSt with a layer thickness of 26 nm. A third dielectric layer is configured on this second metal layer with SnO_(x) with a layer thickness of 50 nm. With this coating in particular the first color parameter a* is provided with a value 4, the second color parameter b* with a value −35 and the third color parameter L* with a value 46. Such an embodiment of a coating conveys a visual effect such that the cooktop plate appears with a metallic blue effect.

In a further embodiment provision is made for the coating to have three dielectric layers with SnO_(x), which have layer thicknesses of 100 nm and again 100 nm and 50 nm when viewed from the lower side of the base plate downward. A metal layer comprising SSt is configured in each instance between two such dielectric layers. The first metal layer has a layer thickness of 15 nm and the second metal layer has a layer thickness of 35 nm. In this embodiment the color parameters are such that the first color parameter a* has the value −31, the second color parameter b* has the value 0 and the third color parameter L* has the value 67. With such an embodiment of a coating a visual effect is generated such that the cooktop plate appears metallic green.

In a further exemplary embodiment provision is made for the coating again to have three dielectric layers with SnO_(x), with the first dielectric layer having a layer thickness of 17 nm, the second dielectric layer having a layer thickness of 66 nm and the third dielectric layer having a layer thickness of 50 nm. Here too at least one metal layer is configured in each instance between the dielectric layers, the first metal layer comprising Cu and having a layer thickness of 33 nm. The second metal layer comprises SSt and has a layer thickness of 25 nm. The color parameters are also such that the first color parameter a* has the value −35, the second color parameter b* has the value 5 and the third color parameter L* has the value 60. With such an embodiment of the coating a visual effect is achieved such that the cooktop plate appears metallic red.

In a further exemplary embodiment the coating again comprises three dielectric layers with SnO_(x). The first dielectric layer has a layer thickness of 29 nm, the second dielectric layer has a layer thickness of 41 nm and the third dielectric layer has a layer thickness of 50 nm. Here too at least one metal layer is configured in each instance between the dielectric layers, the first metal layer comprising SiAl and having a layer thickness of 45 nm. The second metal layer comprises SSt and has a layer thickness of 22 nm. The color parameters in this embodiment are such that the first color parameter a* has the value 9, the second color parameter b* has the value −40 and the third color parameter L* has the value 64. Such an embodiment achieves a visual effect such that the cooktop plate appears metallic yellow.

In all the embodiments provision is made for a protective anti-oxidation layer to be configured as the lower terminating layer, also being assigned to the coating.

Provision can also be made for the base plate of the cooktop plate also to be printed. Printing can be configured on the front end face or on the surface of the base plate. Markings can also be configured in the base plate itself. These can be produced for example by means of laser light. Such printing allows interface regions or operating fields to be marked. The peripheral boundaries of cooking zones can also be marked. Printing can take place for example using screen printing methods or by means of laser marking. Lasers can also be used to configure corresponding markings at different height levels in the interior of the base plate. Further options for this are set out in DE 10 2006 017 250 A1.

A protective layer of the coating configured in a downward direction can also be produced by means of a protective film, which is configured for example by a tint, polymer material or ceramic material. Application here can also take place by means of printing or spraying. Such printing is preferably configured with a thickness of several 100 μm.

It is possible, in particular by applying the layers of the coating by means of PVD (physical vapor deposition) methods, for the layer thicknesses of the individual layers to be produced very precisely, thereby allowing the visual optical effect in respect of the presentation of display elements, illuminating means, such as for example light-emitting diodes, and images to be identified through the coating. It is also possible for mechanical units disposed below and further physical components not to be visible when looking at the cooktop plate from above when said cooktop plate is disposed in a cooktop.

Such an embodiment of a coating of the cooktop plate, optionally with additional printing, means that a surface region, which shows the operating apparatus on the cooktop plate, is also presented with a uniform visual appearance.

The overall layer thickness of the coating below the lower side is preferably between 10 nm and 500 nm.

The proposed embodiment of a coating below the cooktop plate allows a very wide range of colored metallic impressions to be generated for a cooktop plate, it being possible to configure a very wide range of colorings by modifying the number of layers, the materials and the layer thicknesses with the respective color parameters.

Further features of the invention will emerge from the claims, figures and description of the figures. The features and feature combinations cited above in the description and the features and feature combinations cited below in the description of the figures and/or illustrated in the figures alone can be used not only in the respectively cited combination but also in other combinations or alone, without departing from the scope of the invention.

Exemplary embodiments of the invention are described in more detail below with reference to schematic drawings, in which:

FIG. 1 shows a schematic perspective view of an exemplary embodiment of an inventive cooktop;

FIG. 2 shows a sectional diagram through the cooktop plate of the cooktop according to FIG. 1;

FIG. 3 shows a diagram, in which the degree of transmission and the degree of reflection are shown as a function of wavelength for a first exemplary embodiment of an inventive cooktop plate;

FIG. 4 shows a diagram, in which the degree of transmission and the degree of reflection are shown as a function of wavelength for a second exemplary embodiment of an inventive cooktop plate;

FIG. 5 shows a diagram, in which the degree of transmission and the degree of reflection are shown as a function of wavelength for a third exemplary embodiment of an inventive cooktop plate; and

FIG. 6 shows a diagram, in which the degree of transmission and the degree of reflection are shown as a function of wavelength for a fourth exemplary embodiment of an inventive cooktop plate.

Identical elements or those of identical function are shown with identical reference characters in the figures.

FIG. 1 shows a schematic and perspective view of a cooktop 1, which comprises a cooktop plate 2, which has a base plate 3, which is made of glass or glass ceramic. Four cooking zones 5, 6, 7 and 8, the number and positions of which are shown by way of example, are shown on an upper side 4 of the base plate 3. A coating 10 (not shown in detail in FIG. 1) is configured on a lower side 9 of the base plate 3, having at least two metal layers and at least two dielectric layers as well as a protective anti-oxidation layer.

FIG. 2 shows a sectional diagram through the cooktop plate 2 according to the diagram in FIG. 1. The thickness ratios are not to scale and in particular the base plate 3 is much thicker than the overall layer thickness of the coating 10. In the illustrated embodiment provision is made for the coating 10 to comprise a first dielectric layer 11 directly adjoining the lower side 9. Configured to follow this in a downward direction is a first metal layer 12. Configured to follow this again in a downward direction is a second dielectric layer 13. Configured to follow this again is a second metal layer 14. Configured then in a downward direction is a third dielectric layer 15. This layer composition is terminated in a downward direction by a protective layer, which is a protective anti-oxidation layer 16.

Provision can also be made for further metal layers and further dielectric layers also to be provided.

In a first exemplary embodiment provision is made for the first dielectric layer 11 to have a layer thickness of 76 nm and to comprise a material SnO_(x). In this exemplary embodiment provision is made for the first metal layer 12 then to have a layer thickness of 18 nm and for the material to be SSt. The second dielectric layer 13 is configured with a layer thickness of 78 nm and comprises SnO_(x) as its material.

The second metal layer 14 is configured with a layer thickness of 26 nm and comprises the material SSt. Following this the dielectric layer 15 is then configured with a layer thickness of 50 nm, the material again being SnO_(x). The number 2 in particular is provided in respect of the factor x, as is also the case for the other exemplary embodiments cited above.

The first color parameter a* has a value 4, the second color parameter b* has a value −35 and the third color parameter L* has a value 46. As can be seen in the diagram according to FIG. 3 relating to this exemplary embodiment, the degree of transmission of the cooktop plate 2 in the wavelength range between 380 nm and 780 nm is <10%. In contrast the degree of reflection in the wavelength range between 380 nm and around 430 nm rises from around 15% to just under 40%, to drop again continuously to be <10% from a wavelength of around 580 nm.

The degree of reflection R here is characterized by the curve K2 and the degree of transmission is characterized by the curve K1.

In a further exemplary embodiment provision is made for the dielectric layers 11, 13 and 15 to be made of the material SnO_(x). The layer thickness of the first dielectric layer 11 is 100 nm. The layer thickness of the second dielectric layer 13 is also 100 nm. The layer thickness of the third dielectric layer 15 is 50 nm. In this exemplary embodiment the two metal layers 12 and 14 are made of the material SSt, with the first metal layer 12 having a layer thickness of 14 nm and the second metal layer 14 having a layer thickness of 35 nm. In respect of the color parameters provision is made in this embodiment for the first color parameter a* to have the value −31, the second color parameter b* to have the value 0 and the third color parameter L* to have the value 67. The diagram according to FIG. 4 is shown in respect of this embodiment. Here too the degree of transmission according to the curve K1 is <10%, in particular <7%, over the entire wavelength range between 380 nm and 780 nm. The degree of reflection R according to the curve K2 again rises here from the wavelength 380 nm to around 500 nm from around 7% to just under 50%, to then drop continuously again. The degree of transmission T is less than 10% in particular from a wavelength of around 660 nm.

In a further third exemplary embodiment provision is made for the dielectric layers 11, 13 and 15 to be made of the material SnO_(x) again. The first dielectric layer 11 has a layer thickness of 17 nm, the second dielectric layer 13 has a layer thickness of 66 nm and the third dielectric layer 15 has a layer thickness of 50 nm.

The two metal layers 12 and 14 configured therebetween are such that the first metal layer 12 is made of Cu and the second metal layer 14 is made of SSt. The first metal layer 12 has a layer thickness of 33 nm, while the second metal layer 14 has a layer thickness of 25 nm. In this embodiment the first color parameter a* has a value of −35, the second color parameter b* has the value 5 and the third color parameter L* has the value 60.

The diagram according to FIG. 5 illustrates this embodiment, with the degree of transmission T according to the curve K1 again being less than 10%, in particular <8%, over the entire wavelength range. In respect of the degree of reflection R the curve K2 shows a rise from the wavelength 380 nm to around 410 nm, to fall again and rise again from a wavelength of around 560 nm.

In a further specific exemplary embodiment provision is made for the three dielectric layers 11, 13, 15 to be made of the material SnO_(x) again. The layer thicknesses here are 29 nm for the first dielectric layer 11, 41 nm for the second dielectric layer 13 and 50 nm for the third dielectric layer 15. The two metal layers 12 and 14 are designed so that the first metal layer 12 is made of SiAl and has a layer thickness of 45 nm. The second metal layer 14 is made of SSt and has a layer thickness of 22 nm. In this embodiment the first color parameter a* has the value 9, the second color parameter b* has the value −40 and the third color parameter L* has the value 64. FIG. 6 shows the associated diagram, with the degree of transmission T being shown by the curve K1 and the degree of reflection R being shown by the curve K2 in profile over the wavelength here too. The degree of transmission T is also <10% over the entire wavelength range between 380 nm and 780 nm here.

LIST OF REFERENCE CHARACTERS

-   1 Cooktop -   2 Cooktop plate -   3 Base plate -   4 Upper side -   5, 6, 7, 8 Cooking zones -   9 Lower side -   10 Coating -   11 First dielectric layer -   12 First metal layer -   13 Second dielectric layer -   14 Second metal layer -   15 Third dielectric layer -   16 Protective anti-oxidation layer -   K1, K2 Curves -   T Degree of transmission -   R Degree of reflection 

1-15. (canceled)
 16. A cooktop plate, comprising: a base plate having a lower side; and a coating formed on the lower side of the base plate and including at least two metal layers and at least two dielectric layers in such a manner that a first color parameter a* or a second color parameter b* of the cooktop plate has a value greater than +10 or smaller than −10.
 17. The cooktop plate of claim 16, wherein the coating is configured such that a degree of transmission of the cooktop plate in the wavelength range between 380 nm and 780 nm is less than 12%.
 18. The cooktop plate of claim 16, wherein the coating is configured such that a degree of transmission of the cooktop plate in the wavelength range between 380 nm and 780 nm is between 0.5% and 10%.
 19. The cooktop plate of claim 16, wherein the coating is configured such that a third color parameter L* has a value greater than
 40. 20. The cooktop plate of claim 16, wherein the coating is configured such that a third color parameter L* has a value between 40 and
 70. 21. The cooktop plate of claim 16, wherein the coating has a number of metal layers which is 2 or
 3. 22. The cooktop plate of claim 16, wherein the coating has a number of dielectric layers which is between 2 and
 4. 23. The cooktop plate of claim 16, wherein the coating includes a protective layer as a lower termination.
 24. The cooktop plate of claim 23, wherein the protective layer is a protective anti-oxidation layer.
 25. The cooktop plate of claim 16, wherein the metal layers and the dielectric layers respectively have layer thicknesses less than or equal to 300 nm.
 26. The cooktop plate of claim 16, wherein the metal layers and the dielectric layers respectively have layer thicknesses less than or equal to 100 nm.
 27. The cooktop plate of claim 16, wherein the at least two metal layers of the coating have different layer thicknesses or the at least two dielectric layers of the coating have different layer thicknesses.
 28. The cooktop plate of claim 16, wherein the metal layers and the dielectric layers of the coating are formed by sputtering on the lower side.
 29. The cooktop plate of claim 28, wherein the sputtering includes magnetron sputtering.
 30. The cooktop plate of claim 16, wherein one of the metal layers is made of a material selected from the group consisting of the elements SSt, Mo, Ni, Cr, Nb, V, Ti, Ta, Si, Al, Cu, W, and a combination of at least two of said elements.
 31. The cooktop plate of claim 16, wherein one of the dielectric layers is made of a material selected from the group consisting of the compounds SnO_(x), ZnO_(x), TiO_(x), AlO_(x), SiO_(x), NbO_(x), TaO_(x), SiN_(x), AlN_(x), TiN_(x), CrN_(x), and a combination of at least two of said compounds.
 32. The cooktop plate of claim 19, wherein a first one of the dielectric layers of the coating includes SnO_(x) with a layer thickness of 76 nm, with the first dielectric layer being followed by at least a first one of the metal layers which includes SSt with a layer thickness of 18 nm, followed by a second one of the dielectric layers which includes SnO_(x) with a layer thickness of 78 nm, followed by at least a second one of the metal layers which includes SSt with a layer thickness of 26 nm, said coating having a third dielectric layer which includes SnO_(x) with a layer thickness of 50 nm and is applied upon the second metal layer, wherein the value of the first color parameter a* is 4, the value of the second color parameter b* is −35, and the value of the third color parameter L* is
 46. 33. The cooktop plate of claim 19, wherein a first one of the dielectric layers of the coating includes SnO_(x) with a layer thickness of 100 nm, with the first dielectric layer being followed by at least a first one of the metal layers which includes SSt with a layer thickness of 14 nm, followed by a second one of the dielectric layers which includes SnO_(x) with a layer thickness of 100 nm, followed by at least a second one of the metal layers which includes SSt with a layer thickness of 35 nm, said coating having a third dielectric layer which includes SnO_(x) with a layer thickness of 50 nm and is applied upon the second metal layer, wherein the value of the first color parameter a* is −31, the value of the second color parameter b* is 0, and the value of the third color parameter L* is
 67. 34. The cooktop plate of claim 19, wherein a first one of the dielectric layers of the coating includes SnO_(x) with a layer thickness of 17 nm, with the first dielectric layer being followed by at least a first one of the metal layers which includes Cu with a layer thickness of 33 nm, followed by a second one of the dielectric layers which includes SnO_(x) with a layer thickness of 66 nm, followed by at least a second one of the metal layers which includes SSt with a layer thickness of 25 nm, said coating having a third dielectric layer which includes SnO_(x) with a layer thickness of 50 nm and is applied upon the second metal layer, wherein the value of the first color parameter a* is −35, the value of the second color parameter b* is 5, and the value of the third color parameter L* is
 60. 35. The cooktop plate of claim 19, wherein a first one of the dielectric layers of the coating includes SnO_(x) with a layer thickness of 29 nm, with the first dielectric layer being followed by at least a first one of the metal layers which includes SiAl with a layer thickness of 45 nm, followed by a second one of the dielectric layers which includes SnO_(x) with a layer thickness of 41 nm, followed by at least a second one of the metal layers which includes SSt with a layer thickness of 22 nm, said coating having a third dielectric layer which includes SnO_(x) with a layer thickness of 50 nm and is applied upon the second metal layer, wherein the value of the first color parameter a* is 9, the value of the second color parameter b* is −40, and the value of the third color parameter L* is
 64. 